The need for protective eyewear in various hazardous situations, especially those involving military personnel, is well known. However, given the extreme variability of the risk posed and other pertinent factors, it is extremely difficult to design a single system that will protect against all eventualities. Thus, a system that protects against ballistic impacts may not protect against laser radiation. On the other hand, a suitable laser-protective system may have a visual transmittance too low for use in low-light applications. The needs of eyeglass wearers (ametropes) present design problems not encountered when working with persons of normal vision (emmetropes). In general, features that are necessary in a given situation, such as goggles for protection against wind or dust, are unnecessary or undesirable in more normal situations. However, despite this need for eyewear suitable for specific situations, it is impractical to provide each wearer with a different eyewear system for each hazard that might be encountered.